1. Field of Invention
This invention relates to rapidly-scanned laser systems that utilize a data set to project a precise image onto a precisely located region of a work surface.
Although the laser beam illuminates only one spot at a time, it moves so rapidly that an entire image on the surface becomes apparent to the eye.
The work surface upon which the image is projected may be a forming mold, a mandrel, or a completed or partially completed work piece. The image is used to provide an assembly and alignment aid for objects to be positioned on the work surface or for other activities to be performed on or in relation to the surface upon which the image is projected.
An exemplary application is the hand layup of composite parts in the aerospace industry, such as wings and engine nacelles. Another exemplary application is the projection of outlines of large roof trusses. Numerous other applications are possible.
2. Prior Art
U.S. Pat. Nos. 5,341,183, 5,400,132, 5,444,505, 5,450,147 and 5,506,641 all relate to a rapidly-scanned laser projection system utilizing a three-dimensional data set projected onto a contoured surface. These laser projection systems are referred to as "Optical Layup Templates" (OLTs). They envision a single laser with fixed wavelength (see e.g. U.S. Pat. No. 5,506,641, col. 1 line 33).
U.S. Pat. No. 5,430,662 refers to a laser positioning system for roof truss manufacturing. In this application each projector is envisioned as having a single Helium-Neon laser.
Early OLT laser projection systems utilized red Helium-Neon (HeNe) lasers because of their low cost and long, dependable life. Out of laser safety considerations, and the risk of inadvertent ocular exposure of workers to the laser beam, the laser output power, however, has been limited to less than what would otherwise be desirable for easy viewing in high ambient lighting. Color research indicates that the human eye is most sensitive to light in the yellow-green region. Several manufacturers have therefore offered OLT devices with a choice to the buyer of having either a green or a red laser installed at the factory.
In the different field of laser light shows, multi-color beams are often produced by a gas laser that lases at several lines simultaneously. These lines are separated and controlled individually by acousto-optic modulators (AOMs), that enable multichromatic projected renderings. The projections are used for entertainment purposes and are not precisely related to features of surfaces upon which the beam projects. Other laser arrangements may also be employed.